<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
       var arr = [];
       for (var index = 0; index < 10; index++) {
          arr[index] = function(){
              console.log(index);
          }
       }
       arr[6]();//6? 5? 结果是10
    </script>
</body>
</html>